It's Legs.
Lets look at some examples.
Zabuza had legs.
Obito had Legs.
Nagato had legs, then replaces them with 12 others.
Madara is literally 100% Legs.
Konan was a villain, and then she stopped being one. What happened?You must be registered for see links
Itachi pretended to be a villain, thenYou must be registered for see links
Fun fact, Kaguya's legs have never been seen. Presumably this is because she is not a proper villain.
Real villains need to destroy a whole village in 5 minutes